Pitot tube for pitot pump

ABSTRACT

A pitot tube for a pitot pump, i.e., a centrifugal pump comprising a rotary casing, means for delivering a fluid to be pumped to the rotary casing, and a discharge duct coaxial with the rotary casing. The pitot tube is disposed in and extends radially of the rotary casing and is provided adajcent its outer end with an inlet facing in a direction opposite to the direction of rotation of the rotary casing, whereby the inlet receives fluid from adjacent the periphery of the rotary casing with a ram effect. The pitot tube includes axially spaced side walls and is provided adjacent its inner end, and in one of such side walls, with an outlet communicating with the discharge duct and coaxial with the rotary casing. Within the pitot tube is a flow splitting vane which extends from one side wall to the other, such vane extending from adjacent the outlet to adjacent the outer end of the pitot tube and dividing the pitot tube into two compartments spaced apart circumferentially of the rotary casing, one compartment being adjacent the leading edge of the pitot tube and the other adjacent the trailing edge thereof. This vane has the effect of streamlining the fluid flow through the outlet of the pitot tube and into and through the discharge duct, thereby minimizing flow losses.

United States Patent n 1 Erickson PITOT TUBE FOR PITOT PUMP [75] Inventor: John W. Erickson, Huntington Beach. Calif.

[73] Assignee: Kobe Inc., Huntington Park. Calif.

[22] Filed: Aug. 14, 1972 21 Appl. No.: 280,677

1,217,895 12/1959 France 415/89 Primary ExaminerC. J. Husar Att0rneyFord W. Harris, Jr. et a1.

[57] ABSTRACT A pitot tube for a pitot pump, i.e., a centrifugal pump 11 3,776,658 1 1 Dec. 4, 1973 comprising a rotary casing, means for delivering a fluid to be pumped to the rotary casing, and a dis- 9 charge duct coaxial with the rotary casing. The pitot tube is disposed in and extends radially of the rotary casing and is provided adajcent its outer end with an inlet facing in a direction opposite to the direction of rotation of the rotary casing, whereby the inlet receives fluid from adjacent the periphery of the rotary casing with a ram effect. The pitot tube includes axially spaced side walls and is provided adjacent its inner end, and in one of such side walls, with an outlet communicating with the discharge duct and coaxial with the rotary casing. Within the pitot tube is a flow splitting vane which extends from one side wall to the other, such vane extending from adjacent the outlet to adjacent the outer end of the pitot tube and dividing the pitot tube into two compartments spaced apart circumferentially of the rotary casing, one compartment being adjacent the leading edge of the pitot tube and the other adjacent the trailing edge thereof. This vane has the effect of streamlining the fluid flow through the outlet of the pitot tube and into and through the discharge duct, thereby minimizing flow losses.

8 Claims, 13 Drawing Figures PITOT TUBE FOR PITOT PUMP BACKGROUND OF INVENTION is provided adjacent its outer end with an inlet adjacent the periphery of the rotary casing and facing in a direction opposite to the direction of rotation of the rotary casing. The pitot tube is provided adjacent its inner end with an outlet communicating with the discharge duct.

Centrifugal pumps of the foregoing type are well known and have the advantage of providing a very simple structure for pumping fluids at high pressures and in relatively large volumes. A pitot pump typical of the .prior art is disclosed in Pat. No. 3,384,024, granted May 21, 1968 to William L. King.

SUMMARY AND OBJECTS OF INVENTION I The primary object of the present invention is to minimize flow losses in the pitot or pickup tube of a centrifugal pump of the type hereinbefore outlined.

Summarizing, an important object is to provide a pitot tube provided therein with a flow splitting vane which extends from one side wall of the pitot tube to the other and which extends from adjacent the outlet of the pitot tube to adjacent the outer end thereof, this vane dividing the pitot tube into two compartments spaced apart circumferentially of the rotary casing and respectively located adjacent the leading and trailing edges of the pitot tube. Related objects are to provide a construction wherein the vane traverses and bisects the outlet, wherein the vane extends laterally into the outlet, and wherein the vane and the trailing edge of the pitot tube converge from adjacent the inner end of the vane toward the outer end thereof.

With the foregoing construction, flow through the pitot tube and into and through the discharge duct is streamlined to reduce flow losses. I have found that, without the flow splitting vane of the invention, a severe vortex is created within and/or adjacent the outlet of the pitot tube, resulting in high flow losses. Such losses are greatly reduced by the flow splitting vane of the invention, which is an important feature.

The foregoing objects, advantages, features and results of the present invention, together with various other objects, advantages, features and results which will be evident to those skilled in the pitot pump art in the light of this disclosure, may be achieved with the exemplary embodiment of the invention illustrated in the accompanying drawings and described in detail hereinafter.

DESCRIPTION OF DRAWINGS FIG. I is a longitudinal sectional view ofa pitot pump equipped with a pitot or pickup tube which embodies the invention;-

FIG. 2 is an enlarged, transverse sectional view showing the pitot tube of the invention, FIG. 2 being taken as indicated by the arrowed line 22 of FIG. 1, and also by the arrowed line of FIG. 3;

FIG. 3 is a sectional view taken as indicated by the arrowed line 33 of FIG. 2;

FIGS. 4 and 5 are sectional views through the strut of the pitot tube and are taken as indicated by the arrowed lines 44 and 55, respectively, of FIG. 2; and

FIGS. 6, 7, 8, 9, 10, 11, 12 and 13 are fragmentary sectionalviews through the trailing or rearward end of the head of the pitot tube and are taken along the arrowed lines 66, 7-7, 8-8, 99, 10-10, 1I-1l, l212 and 13l3, respectively, of FIG. 2 of the drawings.

DESCRIPTION OF EXEMPLARY EMBODIMENT OF INVENTION 4 Referring initially to FIG. 1 of the drawings, illustrated therein is a pitot pump 20 comprising anouter housing 22 containing a rotary casing 24. In the particular construction illustrated, the rotary casing 24 is driven by an electric motor 26 mounted on the housing 22, the rotary casing being supported by the motor shaft 28. However, it will be understood that the rotary casing 24 may be mounted on bearings within the housing 22 itself.

The housing 22 is provided with an inlet 30 for the fluid to be pumped, which inlet communicates with a chamber 32 leading to an annular passage 34 extending into one end wall 36 of the rotary casing 24. Within such end wall are generally radial passages 38 which communicate at their inner ends with the annular passage 34 and which communicate at their outer ends with the interior of the rotary casing 24 adjacent the inner periphery thereof.

Within the rotary casing 24 is a pitot or pickup tube 40 of the invention. The pitot tube 40 is radially oriented and is provided adjacent its outer end with an inlet 42 facing in a direction opposite to the direction of rotation of the rotary casing. The pitot tube 40 is provided adjacent its inner end with an outlet 44 coaxial with the rotary casing 24 and communicating with a discharge duct 46, also coaxial with the rotary casing 24, leading to an outlet 48 in the housing 22. The annular passage 34 surrounds the discharge duct 46 throughout a portion of the length of the latter.

The general mode of operation of the pitot pump 20 is well known so that it does not need to be described in detail. Briefly, the centrifugal force produced by rotation of the casing 24 generates a high fluid pressure adjacent the inner periphery of the casing. The fluid at this high pressure enters the inlet 42 of the pitot tube 40, the pressure being further increased by the ram effect resulting from so orienting the inlet 42 that it faces in a direction opposite to the direction of rotation of the rotary casing 24. The fluid entering the pitot tube 40 flows through the outlet 44 and the discharge duct 46 to the main outlet 48 in the housing 22. It will be understood that the pitot tube 40 is stationary, being mounted on and suitably secured to the discharge duct edge 56. The inner end of the strut 52 is disposed on the opposite side of the axis of rotation from the outer end thereof, and the outlet 44 is formed in one of the side walls 54 between the inner and outer ends of the strut. As best shown in FIGS. 4 and 5, the strut 52, in cross section, has a streamlined configuration with relatively sharp leading and trailing edges 56 and 58.

The head 50 is provided with a rearwardly extending passage 60 which merges smoothly with the outer end of a radial passage 62 in the strut 52, this radial passage leading inwardly to and surrounding the outlet 44. The streamlining of the head 50 will be clear by progressively viewing FIGS. 3, 6, 7, 8, 9, 10, ll, 12, and 13.

An important feature of the present invention is that the radial passage 62 is divided into circumferentially spaced, leading and trailing compartments 64 and 66 by a flow splitting vane 68 which extends from the inner end of the passage 62 substantially to the outer end thereof and which terminates at its outer end in a sharp edge 70. The vane 68 traverses and bisects the outlet 44, as best shown in FIG. 2, and converges toward the trailing edge 58 of the strut 52 so that the trailing compartment 66 becomes progressively smaller in cross sectional area from its inner end toward its outer end, the reverse being true of the leading compartment 64.

The presence of the vane 68 results in smooth, streamlined flow through the passages 60 and 62 and the outlet 44, and into the discharge duct 46, thereby minimizing flow losses. Without the flow splitting vane 68, a severe vortex formed in the outlet 44 and the discharge duct 46 which resulted in very high power losses. These were greatly reduced by the addition of the flow splitting vane 68, which is an important feature.

In addition to the foregoing, various other features of the specific pitot tube configuration disclosed are of importance. Considering one of these, in the area in which FIG. 4 is taken, the ratio of the maximum spacing of the outer surfaces of the side walls 54 to the spacing of the leading and trailing edges 56 and 58 should not be more than about 0.18. With this ratio, flow separation around the pitot tube 40 is avoided, and the drag 4 of the pitot tube is minimized.

Considering another relationship, the cross sectional area of the trailing compartment 66 in the area of FIG. 4 should be approximately half the area of the inlet 42 for minimum flow losses in the bend at the junction of the passages 60 and 62.

Another feature is that the side walls 54 are parallel in the outer portion of the strut 52, and then diverge radially inwardly toward the inner end of the strut, as shown in FIG. 3, to provide a diffuser 72. This construction results in maximum head recovery.

Another feature is that the leading and trailing compartments 64 and 66 are kept as large as possible at their junction with the outlet 44, as shown in FIG. 5, to minimize flow losses in the bend joining these compartments and the outlet. As shown in FIG. 3, the radius at 74 is made as large as practicable to minimize the entrance losses into the outlet 44.

. Although an exemplary embodiment of the invention has been disclosed for purposes of illustration, it will be understood that various changes, modifications and substitutions may be incorporated in such embodiment without departing from the spirit of the invention as defined by the claims hereinafter appearing.

I claim as my invention:

1. In a pitot pump, the combination of:

a. a rotary casing;

b. means for delivering a fluid to be pumped to said rotary casing;

c. a discharge duct coaxial with said rotary casing;

d. a pitot tube in and extending radially of said rotary casing, said pitot tube having adjacent its outer end an inlet facing in a direction opposite to the direction of rotation of said rotary casing, said pitot tube having axially spaced side walls providing therebe tween a radial passage and having circumferentially spaced edges joined to provide said pitot tube with circumferentially spaced leading and trailing edges, said pitot tube having adjacent its inner end, and in one of said side walls, an outlet coaxial with said rotary casing and connecting the inner end of said radial passage to said discharge duct, and said pitot tube further having a circumferentially rearwardly extending passage connecting said inlet to the outer end of said radial passage; and

e. a flow splitting vane in said radial passage in said pitot tube and extending from one side wall of said pitot tube to the other, said vane-extending generally radially from adjacent said outlet to adjacent said outer end of said radial passage in said pitot tube and dividing said radial passage in said pitot tube into two compartments spaced apart circumferentially of said rotary casing, and the outer end of said vane being spaced circumferentially from said inlet by said rearwardly extending passage.

} 2. A pitot tube for a pitot pump, said pitot tube having radially spaced inner and outer ends and having circumferentially spaced leading and trailing edges connected by laterally spaced side walls providing therebetween a radial passage, said pitot tube having adjacent its outer end an inlet facing in the same direction as said leading edge and connected to the outer end of said radial passage by a circumferentially rearwardly extending passage, said pitot tube having an outlet adjacent its inner end and in one of said side walls and communicating with the inner end of said radial passage, said pitot tube having therein a flow splitting vane which is disposed in said radial passage and which extends laterally from one side wall of said pitot tube to the other, said vane extending generally radially outwardly from adjacent said outlet to adjacent said outer end of said radial passage in said pitot tube and dividing said radial passage in said pitot tube into leading and trailing compartments respectively adjacent said lead ing and trailing edges, and the outer end of said vane being spaced circumferentially from said inlet by said rearwardly extending passage.

3. A pitot tube according to claim 2 wherein said vane diametrally traverses and bisects said outlet.

4. A pitot tube as defined in claim 3 wherein said vane extends laterally into said outlet.

5. A pitot tube as set forth in claim 3 wherein said vane and said trailing edge converge from adjacent the inner end of said vane toward the outer end thereof.

6. A pitot tube as defined in claim 5 wherein the minimum cross sectional area of said trailing compartment is about half the cross sectional area of said inlet.

7. A pitot tube according to claim 3 wherein the ratio of the spacing of the outer surfaces of said side walls to the spacing of said leading and trailing edges is not more than about 0.18.

8. A pitot tube as defined in claim 3 wherein the cross sectional area of said radial passage increases toward the inner end thereof to provide a diffuser. 

1. In a pitot pump, the combination of: a. a rotary casing; b. means for delivering a fluid to be pumped to said rotary casing; c. a discharge duct coaxial with said rotary casing; d. a pitot tube in and extending radially of said rotary casing, said pitot tube having adjacent its outer end an inlet facing in a direction opposite to the direction of rotation of said rotary casing, said pitot tube having axially spaced side walls providing therebetween a radial passage and having circumferentially spaced edges joined to provide said pitot tube with circumferentially spaced leading and trailing edges, said pitot tube having adjacent its inner end, and in one of said side walls, an outlet coaxial with said rotary casing and connecting the inner end of said radial passage to said discharge duct, and said pitot tube further having a circumferentially rearwardly extending passage connecting said inlet to the outer end of said radial passage; and e. a flow splitting vane in said radial passage in said pitot tube and extending from one side wall of said pitot tube to the other, said vane extending generally radially from adjacent said outlet to adjacent said outer end of said radial passage in said pitot tube and dividing said radial passage in said pitot tube into two compartments spaced apart circumferentially of said rotary casing, and the outer end of said vane being spaced circumferentially from said inlet by said rearwardly extending passage.
 2. A pitot tube for a pitot pump, said pitot tube having radially spaced inner and outer ends and having circumferentially spaced leading and trailing edges connected by laterally spaced side walls providing therebetween a radial passage, said pitot tube having adjacent its outer end an inlet facing in the same direction as said leading edge and connected to the outer end of said radial passage by a circumferentially rearwardly extending passage, said pitot tube having an outlet adjacent its inner end and in one of said side walls and communicating with the inner end of said radial passage, said pitot tube having therein a flow splitting vane which is disposed in said radial passage and which extends laterally from one side wall of said pitot tube to the other, said vane extending generally radially outwardly from adjacent said outlet to adjacent said outer end of said radial passage in said pitot tube and dividing said radial passage in said pitot tube into leading and trailing compartments respectively adjacent said leading and trailing edges, and the outer end of said vane being spaced circumferentially from said inlet by said rearwardly extending passage.
 3. A pitot tube according to claim 2 wherein said vane diametrally traverses and bisects said outlet.
 4. A pitot tube as defined in claim 3 wherein said vane extends laterally into said outlet.
 5. A pitot tube as set forth in claim 3 wherein said vane and said trailing edge converge from adjacent the inner end of said vane toward the outer end thereof.
 6. A pitot tube as defined in claim 5 wherein the minimum cross sectional area of said trailing compartment is about half the cross sectional area of said inlet.
 7. A pitot tube according to claim 3 wherein the ratio of the spacing of the outer surfaces of said side walls to the spacing of said leading and trailing edges is not more than about 0.18.
 8. A pitot tube as defined in claim 3 wherein the cross sectional area of said radial passage increases toward the inner end thereof to provide a diffuser. 